All indicators flashing (But they're not LEDS!)

[boredatwork]

tldr: if i indicate left, invariably the right one starts flashing and vice versa. they aren't LEDs, they're incandescent bulbs.

hi
gsxr 750k4 due for its MOT and of course this weekend it starts doing this. when i indicate left, after a second or two the right lights flash in sympathy - eg left on, when the left goes of the right blinks a little weaker, then when it goes back to the left. If I take a bulb out, the "wrong side" still flashes. New relay hasnt fixed it. Ive checked the loom visually nothing obvious. Sprayed and cleaned all the various terminating blocks even tho no obvious corrosion. Even happens when I've disconnected the big connector to the front and the dashboard so i dont think its the diode/single indicator bulb issue.

I'm stuck any ideas gratefully received!
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DAS/Test: Passed March 08!
Bikes: CG 125 and k4 750 gsx-r

[Nobby the Bastard]

Bad earth causing the power to find an alternate route to get to earth, via the bulb rather than the earth.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[sickpup]

The indicators will share a common earth which is corroded somewhere in the loom.
As a quick dirty fix you could add additional earths to the indicators.

[boredatwork]

[boredatwork]

so just as an update- new earths didnt work.

but i've new information - if i disconnect the live from one of the bulbs, and select the other side to flash...both sides flash.clearly something is mega shorting so pulling it all apart to look at the wiring.

sigh.
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DAS/Test: Passed March 08!
Bikes: CG 125 and k4 750 gsx-r

[Easy-X]

I don't think there's anything particularly clever going on with the wiring (with regards to the original design) so for both sides to flash it'd have to either be:

1) a faulty indicator switch
2) the left and right wires corroded together somewhere (Black, Light Green)
3) diode array busted in the display, but you've already tested that by disconnecting

If you disconnect the switch cluster the relay wire is light blue (if I'm reading the right diagram.) Jab a wire between light blue and light green, light blue and black to simulate the indicator switch.

For corroded together wires you'd need to break out a multimeter.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[forarainydave]

Sounds like the switch needs investigating. Just check the continuity on the opposite side from the switch (i.e. check the right side wire from the switch when you select left), there should obviously be none. I think a bit of conducting crud may have built up and is shorting, especially if it's a bit of a weaker signal on the opposite side than the one selected.

[JBM]

I’m guessing you’ve got to the bottom of the issue by now, but if not, does your bike have an alarm?

[boredatwork]

[sickpup]

I wish you'd said you had an alarm.
Datatool alarms used to (don't know now) come with 2 diodes to be wired inline with the indicators when this happens.

Its caused by using the same live in the alarm to fire both sides indicators when arming and disarming.